Abstract
A comparison of the developmental rates of different visual functions can offer a clearer understanding of the visual system and reveal whether these functions are mediated by the same or different underlying neural/optical components. In the present study, 255 children (range: 2.7 to 12.4 years) were tested monocularly on grating acuity, vernier acuity, and contrast sensitivity (CS) using similar card-based tests. Grating acuity was measured using the Teller Acuity Cards II. Vernier acuity was measured using the vernier acuity cards. CS was measured at 0.75, 3.0, and 12.0 cpd using CS cards created by our laboratory. Pearson correlation coefficients were calculated to determine the relationship between each dependent measure and age. The strength of each correlation coefficients was taken as an index of developmental rate. The correlation coefficients were compared to determine whether there were significant differences in developmental rates. Vernier acuity demonstrated the most rapid developmental rate (r=-0.64), followed in order by CS at 12 cpd (r=0.58), grating acuity (r=0.55), CS at 0.75 cpd (r=0.44), and CS at 3.0 cpd (r=0.33). However, the rate of vernier acuity development was not significantly faster than that of CS at 12 cpd or grating acuity (both p>.05). Both vernier acuity and CS at 12 cpd demonstrated significantly faster developmental rates than CS at 3 and 0.75 cpd (both p< .05). The results also indicate that vernier acuity surpasses grating acuity and becomes a hyperacuity between 3 and 4 years of age. The finding that the developmental rates of vernier acuity and grating acuity did not differ was surprising as they are speculated to be mediated by different underlying components (grating acuity: retina; vernier acuity: visual cortex). Also, the faster developmental rate of CS at 12 cpd compared to 3 and 0.75 cpd may reflect the existence of different underlying spatial frequency channels.
Meeting abstract presented at VSS 2017